| Donegal to Oberkirch | 810.76 mi (1,304.80 km) |
| Donegal to Obernburg am Main | 799.26 mi (1,286.29 km) |
| Donegal to Obernkirchen | 725.64 mi (1,167.80 km) |
| Donegal to Oberschleissheim | 951.30 mi (1,530.96 km) |
| Donegal to Oberstdorf | 938.59 mi (1,510.51 km) |
| Donegal to Obertraubling | 946.74 mi (1,523.63 km) |
| Donegal to Obertshausen | 779.48 mi (1,254.44 km) |
| Donegal to Oberursel | 764.91 mi (1,231.00 km) |
| Donegal to Ochsenfurt | 841.41 mi (1,354.11 km) |
| Donegal to Ochsenhausen | 898.24 mi (1,445.58 km) |
| Donegal to Ochtrup | 650.71 mi (1,047.22 km) |
| Donegal to Odenthal | 681.19 mi (1,096.27 km) |
| Donegal to Oelde | 698.16 mi (1,123.58 km) |
| Donegal to Oelsnitz | 897.29 mi (1,444.04 km) |
| Donegal to Oer-Erkenschwick | 668.08 mi (1,075.17 km) |
